Brick and wall construction



July 2, 1968 w. E. CARROLL 3,390,502

BRICK AND WALL CONSTRUCTION Filed July l5, 1966 2 Sheets-Sheet 1 ATTORNEYS July 2, 1968 w. E. CARROLL t 3,390,502

2 Sheets-Sheet 2 Filed July 15. 1966 United States Patent 3,390,502 Y BRICK AND WALL CONSTRUCTION William E. Carroll, 373 College St., Macon, Ga. 31201 Filed July 15, 1966, Ser. No. 565,535 13 Claims. (Cl. 5,2-424) l.

This invention relates to improvements in bricks or building blocks andto walls constructed of such bricks or blocks. Y

It is well known that the building of brick or masonry walls and structures in accordancewith conventional bricklaying procedures requires a Substantial degree of care and skill on the part of the brick mason, in order that the resulting wall may be'plumb and level. Thus,l the quality of the finished structure depends almostrentirely on the 'skill and care of the bricklayer, regardless of the quality of the materials employed. Not only is it dilfuclt to accurately lay the bricks and to bond them together with mortar; but in addition, the bricks themselves are subject to variations in size and shape, `which contribute to this diiculty. Therefore, usual bricklaying or brick masonry procedures are both slow and expensive, while effective quality control is difficult to attain.

Even though the brick manufacturer may have fur nished high quality materials, faulty bricklaying practices may nevertheless create criticism or disputes with respect to such factors as variationsiin size", shape, and relative positioning of the bricks in the completed structure,`reecting unfavorablyon the manufacturer even though he had no control whatsoever of the wall construction and no chance to eliminate vbricklayers errors.

With the foregoing considerations in mind, the present invention has for its primary objects tominimize the need for skilled brick masons services in the erection of brick walls or other analogous brick structures, through the utilization in such structures of a vnew and ingenious interlocking and self-positioning type of brick-and of a Iwall structure embodying same.

The bricks, in accordance with the present invention, are so constructed as to permit laccurateand rapid formation `of the wall structure by unskilled or semi-skilled laborers, who are enabled to assemble the Abricks to form the Wall as an incident to the unloading ofthe bricks from a vehicle by which they are delivered to the job site.

Important features and advantages of the inventioninclude the formation of the' respective bricks forprecise, accurate assembly to construct -a'tmly vertical and level wall, despite comparatively wide tolerances in-size and shape of the bricks; to `so form and interrelate the bricks that they may be assembled and relatively'interlocked in accurately-predetermined relative positions and in properly-spaced formation prior to the application 'of'any mortar or calking material in the joints or interstices be'- tweenvthem; to provide a Wall vstructure of such vbricks comprising relatively-spaced vertical wall sections which are strongly interconnected or bonded to each other by headers extending across the intervening space between them in such manner that the said space is-continuous and thus adapted to house wiring o'r conduits, to convey heating and/or cooling uids', or to be'flled with an insulating material suchas a conventional polyurethane or other plastic foam which, in addition to lending strength and insulating qualities, may function also as a vapor barrier.

A specifically new and usefulfeature of the invention Y consists in the provision of a wall structure having horizontally-spaced wall sections, bonded together as above mentioned, in which -the two wall sections are completely insulated from each other by an intervening plastic heat insulating material which also extends between the vertically-opposed portions of the lugs or bonding headers,

3,390,502 Patented July 2, 1968 lCC and may be applied in liquid or owable form, to fill the crevices between bricks, to adhesively bond thereto in theymanner of' mortar andato cure into a monolithic continuous insulating filler or barrier between the wall sections.` Since the interlocking means between adjoining bricks will have minimal areas of contactwith the bricks in the preferredenibodiment, their heat-conducting function will be negligible, though it is further contemplated that the keys also may be formed of an insulating mate'rial such as glass, to minimize heat conductivity between the wall sections. y.

In 'carrying out the invention to achieve the foregoing objects, there is' employed a specially-constructed brick having a horizontally-elongated main body or face portion fof usual brick-like configuration, from the rear or inner surface of which extends a relatively-transverse header or lug portion. The face and header'portions are vertically co-extensive, presenting relatively-opposed horizontal upper and lower surfaces.v Although referred to herein as horizontal, it is an important feature of the present invention that the said upper and lower surfaces are not required to be truly horizontal or truly uniformly spaced in the different bricks, unusually wide tolerances being permissible in these respects without impairing the utility of operability of the invention.

An important aspect, of the invention consists in forming in the upper and lower surfaces of each such brick a trio of sockets or indentations arranged so that uniformly-sized and shaped balls or keys, when disposed within relatively vertically-registering and opposed complemental sockets of vertically-adjoining bricks, Will be jointly received in the said sockets and will maintain the respective bricks in vertically-spaced relation as well as in predetermined relative lateral positions. It is important that the tri-os of such sockets in the upper and lower surfaces of each brick be positioned as accurately as is practically possible in vertical registry respectively with each other, with the key-engaging surfaces of the sockets or recesses in the opposite surfaces of each brick disposed in truly parallel planes which are accurately uniformly spaced from each other in all of the bricks. At the Same time, it is an important object of the invention to so arrange the sockets as to provide tolerances such as will permit the balls to seat properly in the sockets, despite slight variations in the relative positions of the respective trios of balls or lkeys, and in which the tolerances are limited to variations in relative lateral or horizontal positions of the keys, while avoiding any tolerances in either the keys or sockets such as would permit any consequential departures of the several courses of brick from their desired disposition parallel to other courses or from their vertically-stacked relation.

The foregoing objects and advantages are all attained in the preferred embodiment of the invention illustrated in the accompanying drawings in which:

FIGURE 1 is an exploded perspective view of an individual brick and some of its associated keys incorporating the features of the invention;

FIGURE 2 is a perspective fragmentary view of a wall structure utilizing the bricks of the instant invention, several of said bricks being illustrated in phantom to more clearly indicate the manner in which they are assembled and interconnected;

FIGURE 3 is a front elevation of a portion of the Wall structure of the invention;

FIGURE 4 is an enlarged fragmentary vertical section on the line 4-4 of FIGURE 3, through one of the interconnections between vertically-adjoining bricks;

FIGURE 5 is a plan view of part of a wall structure of the invention, including a corner portion thereof in which certain of the bricks are modified in shape to adapt them for use in the formation of corners; and

FIGURE 6 is a transverse vertical section on the line 6-6 of FIGURE 3, but modified to include a filling of plastic foam insulation between relatively-spaced sections of the wall.

In the accompanying drawings of the preferred exemplification of the invention and in the detailed description thereof which follows, various details of structure and relationships will be specifically described simply for the purpose of facilitating a clear understanding of the invention and of the best Inode contemplated by me for practicing it. However, I recognize that various of the features and details may be changed or omitted without departing from the invention. Therefore, it is not intended by such detailed description to limit the invention in any manner not specifically required in the appended claims.

Referring now in more detail to the accompanying drawings, the brick wall construction shown in the drawings is formed from the novel building blocks or bricks of the invention such as shown in FIGURE 1 and as hereinafter described in more detail. The wall construction shown in these figures comprises an elongated foundation or footing 10 of concrete, or other conventional construction, formed to have an upwardly-presented horizontal bearing surface 10S, as in FIGURE 2. The wall structure itself comprises a pair of relatively-parallel vertical wall sections, respectively designated W and W in FIGURE 2, which are supported on the horizontal bearing surface of the foundation 10 in laterallyspaced relation to each other.

The two wall sections W and W are identical in their construction, so that the description of the structural details of either wall section as hereinafter set forth will apply equally to both such sections. Each section comprises a plurality of horizontally-extending verticallyalternating courses C and C respectively of identical blocks B, in which each course C is relatively horizontally displaced or staggered with relation to the courses C of both wall sections. Thus, the relatively-adjacent ends of the bricks in a given course are disposed opposite or abreast of the longitudinal mid-points of bricks in vertically-adjacent courses of its own wall section, as well as of laterally-opposed or adjacent courses of the other wall section. As is usual, the blocks or bricks in each course are in vertical registry with those in alternate courses of its own wall section. Therefore, from the exterior, the wall has the appearance of a generally-conventional brick wall.

Each brick B comprises a horizontally-elongated main body or face portion 14 of rectangular parallelepiped configuration and a unitary or integral bonding lug or portion 16 projecting horizontally inwardly of the wall transversely to the major longitudinal axis of the face portion for reception in the space between the adjoining wall sections. Each such bonding lug 16 is preferably of triangular shape in plane and adapted for cooperation with the similar bonding lugs of other blocks or bricks B in the manner hereinafter described. Each such bonding lug 16 projects inwardly from its associated face portion 14 for a distance in excess of half of the width of the space between the adjoining wall sections W and W so as to have an appreciable horizontal overlap with the vertically-registering portions of similar lugs 16 of the adjoining wall section. However, it is desirable that the wall sections be spaced apart sufficiently to provide a gap 17 between the free end of each such lug 16 and the inner surface of the adjoining wall section. With this arrangement, the lugs 16 will be arranged in a series of vertically registering stacks or columns, in each of which the lugs will be relatively interleaved so that the inner end portion of each lug of one wall section will project between vertically-overlying and underlying lugs respectively of the other wall section. In the completed wall structure, all vertically-registering socket areas of the bricks, in conjunction with their associated spherical keys 26, will form a series of continuous vertical columns in the space between the wall sections, to olltribute materially to the load-supporting or bearing strength of the wall, while also functioning to bond or interconnect the respective wall sections in a manner to contribute to the shear strength thereof, and thus to increase the capability of the wall structure to withstand horizontallydirected forces. The generally-triangular shape of each lug 16 minimizes the volume of the hollow space between wall sections, and, therefore, of the amount of concrete or insulating material required to fill such space.

As will be readily apparent from the drawings, each block or brick B is formed with generally-horizontal upper and lower surfaces 18 and 20 respectively, common to both the face portion 14 and the header portion or bonding lug 16 thereof. Formed in the -respective said surfaces are trios of upwardly and downwardly-opening sockets 22 and 24 for reception of spherical keys or balls 26 by means of which the respective bricks and the wall sections comprising same are mutually positioned in accurate relationship to each other and vertically adjacent courses C and C of bricks are accurately vertically related and supported one upon another in vertically-spaced relation, so that the bricks or blocks of a given wall structure may be completely assembled in the course of their unloading from the vehicle which transports them tothe building site.

An extremely important feature of the invention, as earlier mentioned, is that the ball and socket couplings or connections between the respective bricks B are adapted to insure accurate relative positioning and spacing of the respective bricks or blocks, while nevertheless permitting comparatively wide tolerances in the dimensions and configurations of the individual bricks. To this end, the trios of sockets 22 and 24 in the upper and lower surfaces respectively of each brick are arranged to define the three corners of an isosceles triangle, each having its base parallel to the major longitudinal axis of the face portion 14 as well as of the wall structure in its entirety, and having its apex on the bonding lug 16 and in the vertical plane of symmetry of the brick, so that in the erected wall structure, all of the sockets 22 are midway between the face portions 14 of the respective wall sections.

The sockets 22 in the upper faces of -the bricks B will all be of uniform dimensions and of similar configuration, adapted to fixedly position the balls or keys with their centers in a common horizontal plane above the upper surface of each brick. Preferably, the upper sockets 22 'are of conical configuration proportioned to engage the uniformly-dimensioned spherical keys 26 along circles ofcontact 22C of uniform radius and disposed in a common horizontal plane. The lower sockets 24 of each brick are of similar circular cross-sectional shape and size. These lower sockets 24 are provided with fiat bottoms 24b in a common horizontal plane and are of lesser depth than the radius of the balls 26.

Each such lower socket is encircled by a marginal wall 24W of sufficient diameter to provide a predetermined clearance with the key 26 to provide tolerances such as will permit slight variations in the relative horizontal positions of the keys received in a given trio of sockets.

The locations of the contact circles 22C and of the socket bottoms 24b are such yas to permit entry of less than half of one of the spherical keys. Therefore, the keys 26 will coact with the relatively-opposed pairs of cornplementary sockets 22 and 24 to support each course of bricks in spaced relation above an immediately-underlying course, and in addition will serve to relatively-laterally position and interlock the bricks of each wall section against relative shifting in a horizontal plane. Also, through cooperation of the bonding or locking lugs 16, the spherical keys will securely interlock the two wall sections against relative horizontal shifting.

In constructing a wall in accordance with the invention, the footing or foundation 10 of concrete or other suitable material is poured or formed in usual manner to present the horizontal bearing surface 10S. The initial or lower-most course of blocks of each wall section is carefully positioned and leveled, and preferably is bonded to the foundation by means of a conventional bed of motor 28, which may be applied if desired after positioning of the bricks, if these are supported on the foundation by the spherical keys 26 within their downwardlypresented sockets 24. As will be seen, the first course of each wall section W-W' is so disposed that the longitudinal distances or spaces between relatively-adjoining sockets 22-22 and 24-24 of adjacent bricks is exactly. equal to the uniform spacing between the sockets 22-22 and 24-24 in each brick. Such distance may be readily determined by the use of the other bricks and keys 26, employed in obvious manner as gauges or templates. This will result in similar uniform spacing between the respective sockets of adjoining bricks.

After the iirst course of bricks B is thus laid, a spherical key 26 is positioned in each of the upwardly-presented sockets 22 and, if desired, may be cemented in position by conventional epoxy resin or other suitable cement. The next course of bricks or blocks B then is laid, the arrangement being such that the face portion 14 of each brick in each course will span the junction between a pair of adjoining bricks in the preceding course, so that its downwardly-presented sockets 24-24 Will receive the spherical keys 26-26 of relatively-adjoining brick face portions of the lower course of its same wall section, while its header portion or bonding lug 16 will substantially overlie a cooperating header portion or lug 16 from one of the bricks in the other wall section to receive in its socket 24 the spherical key 26 carried by the lastmentioned bonding lug 16. The balls or spherical keys 26 may be cemented Within the downwardly-presented sockets 24 of the respective bricks as well as in the upwardly-presented sockets thereof as will be readily apparent.

Successive courses will be laid in the manner above described until the wall reaches the desired height.

In order to form right angle comers in the wall structure, the shape and disposition of the bonding lugs and of their sockets therein, may be suitably modified in certain of the bricks B1 and B2.

Thus, referring to FIGURE 5, the corner structure in each course of bricks will include one of each of the modified types of brick B1 and B2. Each brick B1 has its bonding lug 16 displace-d toward one end thereof so that the sockets 22 and 24' of the lug may be located at the intersections of vertical planes common to the lug sockets 22 and 24 of the two angularly-disposed wall portions, and in vertical registry with the sockets 22', 24' of the similarly modified bricks B1 of other courses.

Each brick B2 will have its bonding lug 16" shortened to avoid interference with the bonding lug 16' of the adjacent brick Bl of the same course. The sockets 22" and 24" in lug 16 lie in the vertical plane of symmetry of the brick, as in the bricks B, but, as compared with the corresponding sockets of bricks B, are loca-ted vat but half of the distance from the common Vertical plane of the other sockets in the face portion 14" of the brick.

Since the spherical keys 26 will normally serve to position the respective bricks with substantially cle-arance between each other, both vertically and longitudinally, the accuracy of the wall structure will not be adversely affected by comparatively-wide variations in dimension and configuration of individual bricks so long as the accuracy of placement of the sockets 22 and 24 in the respective bricks is preserved. With these relationships accurately maintained, it will be readily apparent tha-t, once the initial course of bricks has been properly placed, the subsequent forrnation of the wall by the application of subsequent courses of brick, even though accomplished by unskilled workmen in the course of unloading such bricks from the delivery vehicle, will result in accurate formation ofthe completed wall structure. The lower sockets 24 of each brick are proportioned only to allow for small tolerances in horizontal positioning, such as will have no significant ill effects in the accuracy of their horizontal placement.

After the wall has been built to its intended height, a suitable calking material such as a conventional plastic calking compound or a suitable mortar or adhesive compound may be applied into the spaces or crevices between adjoining bricks as at 29, preferably by extruding it into such crevices by means of a conventional calking gun.

In the completed wall structure, all portions of the space or hollow between wall sections W-W' communicate with each other through the gaps 17 between the free ends of the lug portions 16 and the adjacent face portions 14 of the bricks as well as through the horizontal crevices between vertically-registering portions of the lugs 16 from the opposed wall sections W and W. Thus, there is provided between the wall face portions a substantial continuous :space which may, if desired, define a dead air space or pocket for insulation purposes, or may be utilized for conducting either cold or hot air through the walls to suitable outlets within the building for heating or cooling purposes. It has been found also that such space is well adapted for filling with a suitable plastic foam, such as polyurethane foam, which, because of its unicellular structure, affords high insulating qualities, and also serves as a moisture barrier between adjoining wall sections. Because of its ability to adhere to and unite the bricks, such polyurethane foam also may be regarded as a cementitious material, having qualities similar to mortar, for interconnecting the bricks and irnparting strength to the structure.

The plastic foam 30, filler material of the type which expands upon setting, when applied as soon in FIGURE 6, will flow into spaces between relatively verticallyspaced registering lugs, to form a continuous monolithic insulating blanket between adjoining Wall sections. The insulating effect is further enhanced where the spherical keys or balls 26, affording the only direct connection between the spaced wall sections, are formed of insulating material such as glass.

Despite the spaced relation between the wall sections, it will be apparent that the wall structure will have quite substantial vertical load-supporting capabilities or compressive strength, as will as lateral strength and rigidity, all of which will be inherent from the specific disposition of the bricks and ball and socket couplings or interconnections between them. With the structure shown, the sockets 22 and 24, and the keys 26 may be of rather substantial diameter compared to the lateral dimensions of the brick material to provide substantially large circles of contact of the keys within the sockets 22 and 24, it being appreciated that the keys 26 will be formed of a suitable material having high compression and shear strength, such as concrete, glass, metal, or the like.

It should be appreciated that the precise shape of the brick as herein illustrated is not essential, but is capable of variation so long as the varied shapes admit of constant relationship between the triangularly-disposed sockets on each brick and provide the crevices between the bricks which may be filled with appropriate seal-,ing and/ or insulating material. Such bricks readily lend themselves to production by usual processes. For instance, they may be formed of clay, extruded in a continuous elongated strip or mass of suitable cross-section, corresponding to the plan shape of the individual bricks; and the bricks may be severed successively from such strip by conventional machinery, along planes of cleavage which coincide with the upper and lower surfaces 18 and 20 of the bricks. The sockets 22 and 24 may be applied by suitably-related gangs of drills, appropriately shaped and interrelated in triangular formation, and disposed to form the sockets in accurately-located triangular groups lying in uniformly-spaced parallel planes. Also, such sockets may be indented or impressed by appropriate mandrels or presses before firing and while the bricks or blocks are still in their plastic state; though, in such case, precautions should be observed to prevent deformation before hardening of the bricks. The generallyconical or frustr-conical shape of the sockets as disclosed in the present embodiment is preferred, both as being adapted for easy formation by drilling, as well as being adapted to facilitate reception of the spherical keys by their tapered or funnel-like formations. However, it will be apparent that the sockets 22 may be of spherical curvature, or of other suitable configuration, while the marginal walls of the lower sockets 24 may be of other than circular cross-section.

Having thus described my invention, I claim:

1. In a brick wall construction, a brick comprising a horizontally-elongated face portion and a bonding lug projecting horizontally and transversely from said face portion, said brick having generally-horizontal upper and lower surfaces common to the face portion and to said lug, and being formed in said surfaces respectively with vertically-registering trios of sockets, each said trio being arranged to define the three corners of an isosceles triangle, said triangles being in relatively-spaced parallel planes, the sockets of the upper said surface all being of similar circular cross-sectional shape and proportioned for encircling line engagement with uniformly-dimensioned spherical keys along circles of contact of similar diameter disposed in a common horizontal plane of the brick, to support said keys in fixed triangular disposition with their centers concentric to the respective sockets in a common horizontal plane above said upper surface; the sockets of the other said surface having fiat bottoms disposed in a common horizontal plane for engagement with said respective keys, and being of lesser depth than the radius of said keys, said last-mentioned sockets including encircling side walls proportioned to permit reception of said keys in abutting relation to the socket bottoms de spite slight variations in the relative horizontal positions of said keys.

2. A brick wall construction formed of a plurality of bricks, each constructed as defined in claim 1, said wall construction including a pair of relatively-parallel vertical wall sections in laterally-spaced relation, each section comprising a plurality of horizontally-extending courses of said bricks with the laterally-opposed courses of the respective sections at similar levels, the bricks of each course of each wall section being in horizontally-overlapping relation respectively with those of vertically-adjoining courses of its own wall section and with those of the relatively laterally-opposed course of the other wall section, said bonding lugs of each wall section being disposed in a series of vertical columns in which the lugs from the respective wall sections alternate vertically with each other, with the sockets of said lugs in each column in accurate vertical registry with each other in oppositelydirected pairs, spherical keys, each received in the sockets of such an opposed pair, the sockets of said brick face portions similarly being in relatively vertically-opposed pairs, each said pair having a similar spherical key therein.

3. A brick wall construction as defined in claim 2, in which said spherical keys support relatively-adjacent courses of brick in vertically-spaced relation, and a continuous monolithic filling of cementitious material is disposed between said wall sections and between verticallyadjoining courses of brick in said wall construction, and united to said bricks to augment the strength of said construction.

4. A brick wall construction as defined in claim 3, in which said filling comprises an expanded plastic insulating material.

5. A brick wall construction as defined in claim 3, in which said spherical keys are of insulating material.

6. A wall construction as defined in claim 3, in which said filler material is of the type which expands upon setting, said spherical keys being cemented in their respective sockets to provide tensile strength for withstanding such expansion.

7. A wall construction as defined in claim 6, in which said spherical keys support relatively-adjacent courses of bricks in predetermined spaced relation.

8. A brick Wall construction as defined in claim 7, in which the said spherical keys in each said column are in vertical registry with each other in a vertical longitudinal plane midway between the said wall sections and cooperate with said lugs to render said columns vertically continuous.

9. The combination defined in claim 7, in which each of said lugs of one wall section has a free end spaced from the other wall section to dene a continuous hollow space between said sections.

10. A wall construction as defined in claim 9, in which the said lugs of each wall section extend in vertical planes transverse to said wall section, the longitudinal extremities of the bricks in relatively-adjacent courses of the said same wall section and in the laterallysopposed course of the other said wall section Ibeing disposed symmetrically on opposite sides of said plane parallel thereto.

11. A wall construction as defined in claim 1, in which the depth at which each said circle of contact is located within the socket is less than the radius of said sphere.

12. A wall construction including a plurality of courses of bricks as defined in claim 1, including said spherical keys jointly received in vertically-opposed sockets of vertically-adjoining bricks to accurately locate, support, and interconnecting a plurality of said bricks in predetermined relation.

13. The structure defined in claim 12, in which said spherical keys are fixedly secured Within the respective said sockets.

References Cited UNITED STATES PATENTS 339,799 4/ 1886 McAllister 52-608 591,788 12/ 1897 Pennie 52-608 1,294,509 2/ 1919 Metzinger 52-563 1,707,409 4/ 1929 Nattkamper 52-5 82 1,879,467 9/ 1932 Pierres 5'2-424 2,064,791 12/ 1936 Faber 52-586 1,725,911 8/ 1929 Graham 46-24 FOREIGN PATENTS 537,792 5/ 1955 Belgium.

538,931 6/1955 Belgium.

470,980 1/ 1951 Canada.

22,568 9/ 1900 Switzerland. 257,322 4/ 1949 Switzerland. 936,604 2/ 1948 France.

OTHER REFERENCES American Builder publication, March 1962, page 125.

FRANK L. ABBOTT, Primary Examiner.

JAMES L. RIDGILL, JR., Examiner. 

1. IN A BRICK WALL CONSTRUCTION, A BRICK COMPRISING A HORIZONTALLY-ELONGATED FACE PORTION AND A BOUNDING LUG PORJECTING HORIZONTALLY AND TRANSVERSELY FROM SAID FACE PORTION, SIAD BRICK HAVING GENERALLY-HORIZONTAL UPPER AND LOWER SURFACES COMMON TO THE FACE PORTION AND TO SAID LUG, AND BEING FORMED IN SAID SURFACES RESPECTIVELY WITH VERTICALLY-REGISTERING TRIOS OF SOCKETS, EACH SAID TRIO BEING ARRANGED TO DEFINE THE THREE CORNERS OF AN ISOSCELES TRIANGLE, SAID TRIANGLES BEING IN RELATIVELY-SPACED PARALLEL PLANES, THE SOCKETS OF THE UPPER SAID SURFACE ALL BEING OF SIMILAR CIRCULAR CROSS-SECTIONAL SHAPE AND PROPORTIONED FOR ENCIRCLING LINE ENGAGEMENT WITH UNIFORMLY-DIMENSIONED SPHERICAL KEYS ALONG CIRCLES OF CONTACT OF SIMILAR DIAMETER DISPOSED IN A COMMON HORIZONTAL PLANE OF THE BRICK, TO SUPPORT SAID KEYS IN FIXED TRIANGULAR DIPOSITION WITH THEIR CENTERS CONCENTRIC TO THE RESPECTIVE SOCKETS IN A COMMON HORIZONTAL PLANE ABOVE SAID UPPER SURFACE; THE SOCKETS OF THE OTHER SAID SURFACE HAVING FLAT BOTTOMS DISPOSED IN A COMMON HORIZONTAL PLANE FOR ENGAGEMENT WITH SAID RESPECTIVE KEYS, AND BEING OF LESSER DEPTH THAN THE RADIUS OF SAID KEYS, AND LAST MENTIONED SOCKETS INCLUDING ENCIRCULING SIDE WALLS PROPORTIONED TO PERMIT RECEPTION OF SAID KEYS IN ABUTTING RELATION TO THE SOCKET BOTTOMS DESPITE SLIGHT VARIATIONS IN THE RELATIVE HORIZONTAL POSITIONS OF SAID KEYS. 